Old Rheem - High Pressure Trips in Cooling When Overnight ODT < Setpoint

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Old Rheem - High Pressure Trips in Cooling When Overnight ODT < Setpoint

As discussed in other threads, I've had recent issues with 1999 model Rheem HP condenser tripping high pressure switch in cooling mode. It appeared to be corrected when I switched back to a MERV 8 filter and sealed a 17cfm return leak, which may have allowed hot, moist air to enter the air handler from the attic.

Not so corrected! The overnight temps here in Central Florida have finally started dipping below 75*, but still need cooling to maintain comfort due to high overnight humidity. I have not switched my "manual" tstat to heating, and probably won't, unless it gets really cold in January as it did 2 years ago.

It seems if I keep the tstat at 75* during the day, then turn it down late in the evening to 72* or so, to keep it just below the overnight ODT, it keeps running like a charm, day and night. But, if i forget to lower the tstat, or don't do it until really, really late (like last night), the high pressure switch will trip if the overnight ODT is below the setpoint.

I'll likely call my home warranty company sooner or later, if I get really tired of going out to push the red button when i forget to lower the tstat setpoint. In the meantime, does anybody have a clue as to what may be causing the high pressure switch to trip in cooling under the conditions described? I'd like to give the home warranty tech some suggestions as to what he can check, being as he likely won't be able to duplicate the conditions during daylight hours.

Because its in south Florida, corroded and she wants a new energy efficient unit that will keep her more comfortable.

Yep, sure do.

Reset it after midnight last night and it worked all night, no problem. Was working when I left the house to go to lunch. Got back and it was off again. Reset it again, but this time the compressor fan squealed a bit but wouldn't start. So I just shut it off, put the fan on continuous, opened the windows, and called the home warranty company.

Hoping they condemn it this time so I can get a down payment on a new unit! They put $564 into fixing leaks and changing the accumulator in July, so it's a money pit for them.

Sounds like the fan motor is weak or stopping at times causing the high pressure trip. I wouldn't hold my breath on the home warranty co condemning the unit, they will change the motor as dumb as it is that's how they operate. Cheap cheap cheaper

Reset it after midnight last night and it worked all night, no problem. Was working when I left the house to go to lunch. Got back and it was off again. Reset it again, but this time the compressor fan squealed a bit but wouldn't start. So I just shut it off, put the fan on continuous, opened the windows, and called the home warranty company.

Hoping they condemn it this time so I can get a down payment on a new unit! They put $564 into fixing leaks and changing the accumulator in July, so it's a money pit for them.

Yes its a money-pit....and it is for them, not the warranty company you are paying the premiums to. And they have to get approval thru the company you are paying the "premiums" to. They are doomed!!!!

Yes its a money-pit....and it is for them, not the warranty company you are paying the premiums to. And they have to get approval thru the company you are paying the "premiums" to. They are doomed!!!!

Not sure I'm following you. Who is doomed?

Yes, the "service provider" in the warranty company's "network" of contractors has to get approval from them before they do a repair. The warranty company paid the last "service provider" $564 and they paid another "service provider" an unknown sum in Jan 2010 to replace the TXV. They'll either pay this new "service provider" (different contractor) to fix the current problem, or they'll condemn the unit and pay me a cash-out amount so I can negotiate a replacement. Regardless, I pay the "service provider" $75 for the service call and I pay my annual premiums that cover all the other appliances, electric, plumbing, etc. in my house. So far, this home warranty company has consistently paid out more in repairs than I've paid in premiums over the past 6 years, between this house in FL and where I moved from in VA.